The present invention disclosed herein relates to a hybrid laser diode, and more particularly, to a resonator of a hybrid laser diode.
A hybrid laser diode using a hybrid combination of a silicon and a Group III-V compound semiconductor gains in importance as a light source for silicon photonics technology that merges an optical device and an electronic device.
When this hybrid laser diode is used as a light source for information transmission, a laser diode operating in a single mode is required to improve transmission quality.
With the advent of a Silicon On Insulator (SOI) substrate, a structure of a silicon optical waveguide becomes possible. Accordingly, an optical device can be integrated into an electronic device of a silicon substrate. This new research field is called silicon photonics. However, the silicon itself cannot have a gain in a wavelength band for optical communication, and thus an external light source must be used. In order to resolve this limitation, researches for a hybrid laser diode using wafer bonding technology between a compound semiconductor and a silicon have been recently conducted.
Since a hybrid laser diode is manufactured using the wafer bonding technology, a technique for forming a structure of diverse forms through a re-growth method, which is used for a compound semiconductor laser diode, cannot be used for the hybrid laser diode.
An important factor determining the performance of the hybrid laser diode is a structure of a compound semiconductor waveguide. A structure that may be be used for this compound semiconductor waveguide includes a ridge waveguide and a slap waveguide. When the compound semiconductor structure is the ridge waveguide, a single mode waveguide is formed even if a sectional area of a silicon waveguide is small and has an advantage that a high carrier confinement characteristic is obtained. However, there is a disadvantage that a leakage current occurs due to a surface recombination effect at the surface of the compound semiconductor waveguide exposed to the external. Unlike this, when the compound semiconductor waveguide structure is the slap waveguide, the slap waveguide basically supports a multi-mode and also an impurity region confining a carrier needs to be formed using an ion implantation technique to improve the carrier confinement characteristic. However, it is difficult to form the width of the impurity region to be small and accurate. As a result, it is difficult to oscillate a stable fundamental mode.